Magnetic random access memory (MRAM) can be used as a non-volatile memory.
As a low-power consumption device capable of retaining data even when no power is supplied, MRAM is also suitable for reducing cell size, and is thus being adopted as a next generation memory device.
Therefore, it appears that dynamic RAM (DRAM), static RAM (SRAM), and flash memory devices may be replaced by magnetic memory devices, which can be applied in personal computers, mainframe computers, smart cards, portable computers, mobile communication terminals, telephones, televisions, and other electronic devices.
A magnetic memory device typically uses a magnetic tunnel junction (MTJ) with an insulating layer inserted between a fixed layer and a freely switchable layer.
A magnetic memory device can store different values of contact resistances manifested with the magnetic moment of the fixed layer and the magnetic moment of the freely switchable layer inversed as digital states D0 and D1, respectively. The digital states of the magnetic memory device can generally be sustained as long as no external magnetic field is applied exceeding the anti-magnetic field of the freely switchable layer.
The magnetic memory device can sense the stored digital states by either supplying a current to the MTJ to measure the applied voltage at the junction or by measuring a flowing current with an applied predetermined voltage.